Modern elevator installations or so-called firefighters' elevators designed specifically therefor have to ensure reliable operation even in the event of a fire, on the one hand in order for individuals or at-risk material to be evacuated from the floors affected by the fire, but on the other hand also for transporting the firefighters and their extinguishing equipment. In both cases, the use of extinguishing water—whether by means of a sprinkler installation or on the part of the fire department or both—must not result in the elevator installation or the firefighters' elevator no longer functioning.
This means that the electrical components of the elevator installation have to remain dry. Furthermore, the supporting and driving means must not become so wet as to result in uncontrollable slippage between the driving pulley and the supporting and driving means. Slippage can occur particularly easily because the extinguishing water can have a direct adverse effect on the coefficients of friction between the driving pulley and the supporting and driving means, and/or can change the viscosity of any lubricants, and, on the other hand, it usually contains soap for better firefighting purposes.
The slippage occurring between the driving pulley and supporting and driving means thus gives rise to a reduction in traction or even to a complete loss of traction of the elevator installation and—if there is a large difference between the weight of the elevator car and the weight of the counterweight—possibly to uncontrolled movement of the elevator car, which has to be stopped by its safety brake. However, the satisfactory function of the safety brake or the braking deceleration of the brake shoes thereof on the guide rail, in turn, can also only be ensured when the brake shoes or the guide rail are not moistened with (soap-containing) extinguishing water.
All these requirements make it necessary for the extinguishing water to be drained off and/or intercepted in a controlled manner. The extinguishing water normally penetrates into the elevator shaft via the doors of the latter. International publication WO A1 98/22381 discloses an elevator installation having a drainage system on the shaft doors and flow barriers interengaging with a form fit on each shaft door. The attempt is thus made to keep the elevator shaft free of extinguishing water over its entire height from the outset. The disadvantage with this solution, however, is that high costs are involved in order to equip each floor with corresponding drain pipes and said flow barriers beforehand.